One of the principal tenets of the Ancient commentators on Aristotle was the doctrine that asserted the fundamental harmony of Aristotle and Plato. Recently Lloyd Gerson has come to the defense of this position as a credible reading of Aristotle's relationship to the Academy, while Richard Sorabji, organizer and editor in chief of the massive Commentators project, seems to think that on the whole the idea was outlandish. After all, Aristotle goes out of his way to attack Plato's theory of forms and the immortality of the soul, thus apparently denying the linchpins of Plato's philosophy in toto. But however we may review our readings of Classical philosophy, taking into account for example the implications of Metaphysics Lambda or reading our Plato in light of a developmentalism that sees a rejection of something like a theory of forms (if indeed, we are willing to recognize such in the first place), it is still an interesting question how this method of reading Aristotle through a Platonizing lens, and vice versa, began to evolve in the ancient world.

Riccardo Chiaradonna's book aims to show that Plotinus is actually responsible for the doctrine of harmony, even though his infamously sprawling work, On the Genera of Being, is evidently a series of ad hominem attacks against Aristotle's Categories (ad hominem, in the sense that the treatises are designed to show that Aristotle cannot deliver what he offers in the Categories; he cannot account for everything there is in the terms of a list of ten items, the Categories, of being, quality, quantity, motion, place, relationship, time, etc.).1 According to C., Plotinus' dialectical strategy against Aristotelian positions cleared the way for the later compromise that roughly saw Aristotle as yielding valid results for the sensible world and Platonic tradition as relevant for understanding the intelligible world. C. takes up several chapters of treatise VI.1, the first of Plotinus' three essays on the topic of the categories of being2 and shows both the development of anti-Aristotelian dialectic in Plotinus' own work, as well as the way later commentators responded to Plotinus' attacks. This reading of Plotinus in the light of subsequent commentators such as Porphyry, Iamblichus, Dexippus, and Simplicius is perhaps the most interesting feature of the book. C. also emphasizes the conventionality of Plotinus' own arguments, in the sense that they were a new deployment of Middle Platonist treatments of subjects, particularly the question of what the genus represents.3 Overall, however, the book is largely a rehearsal of a half-century of research into the status of Plotinus' dialectic in this treatise.

Chapter one, Sostanza, is an extended meditation on the dialectical strategy of VI.1.2, where Plotinus considers the Aristotelian notions of the unity of substance and the priority of essence, ousia, as substance in the primary sense. Substance cannot be a common genus that extends over both intelligible and sensible being, for if so, ousia would be a common predicate of the two species of being, intelligible and sensible, and thus could not be either incorporeal or corporeal in itself. But it must be one or the other. Ergo substance is not a genus of both 'species' of being. As Lloyd showed in his terse but brilliant Anatomy of Neoplatonism,4 Plotinus uses an argument that Aristotle had already used against the Platonists: it is not possible to assume under a common and separate genus a hierarchy whose members constitute a naturally prior and posterior series. Lloyd called such a series a P-series and this structure has already been the focus of much research on Plotinus' logic.5

At any rate, C. focuses on the question of whether or not Plotinus' criticisms are unfair, in the sense that he apparently criticizes Aristotle based on the principles of a Platonic ontology. (Plotinus uses the arguments developed already by Middle Platonists such as Lucius and Nicostratus that have been transmitted in Simplicius' own commentary and are evidently derived from the Phaedo's two kinds of being at 79a6.) What does it mean to criticize Aristotle for not recognizing the derivative status of the sensible substance when he is exactly questioning this assumption?6 Thus VI.2.7 has Plotinus at work on the constitution of the sensible essence, where he focuses on the same problems that Aristotle worries about in Metaphysics Zeta: what is substance, really? Is it form, matter or a compound or all three? Although in VI.1.2 Plotinus does not discuss the Aristotelian definition of substance as that which is not said of another and is not in another, it is this criterion that helps Plotinus formulate his radical critique of Aristotelian essentialism in light of the previous traditions, as C. shows. The problem is to distinguish between the way that essence is in matter, apparently vitiating the Aristotelian definition of substance as that which is not in another, and the way that accidents are said to be in their subjects. For Aristotle, only some predicates are used in the category of substance; all other predicates are accidents. What is the difference between these two kinds of predicate? According to C., it is Porphyry who rescues the Aristotelian distinction and supplies a vocabulary which is subsequently adopted by Neoplatonists working in the Categories tradition.

For Porphyry, there are two senses of "subject," ὑποκείμενον: the first sense is matter deprived of quality. The second sense refers to the subject determined by a common quality or particular quality. In other words, there are attributes that complete the essence of the proper subject (the subject is already potentially what it will be when it acquires the essential attribute and so these attributes are distinct from accidents). As Porphyry explains in his in cat. 95, 21 (discussed by C. at 74-6),

Essential qualities are those that are complements of substances. Complements are properties the loss of which destroys their subjects. Properties that can be gained and lost without the subject being destroyed would not be essential. Hence the differentia is included under the definition of substance, since it is a complement of substance, and the complements of substances are substances.

More than this specific answer to a Plotinian objection, we find in the history of Categories commentaries a defense of Aristotle in which Porphyry's solutions become the source of subsequent replies to Plotinus, who applied his critique of the Aristotelian Categories wrongly. For Porphyry, Aristotle was not talking about the intelligible world but just about linguistic expressions that referred to sensible substances. Thus C. shows the evolution of a Neoplatonist interpretation of Aristotle according to which Aristotle's Categories and, with it, his essentialism survive, because fundamentally the sensible world can be described only by means of the discursive thinking that Aristotle's language in the Categories captures. Subsequently Neoplatonists accepted this metaphysical division of labor between Aristotelian immanent forms and Platonic transcendent forms and in this sense developed their doctrine of harmony. Thus, Simplicius writes (p. 2, 26-29), Dexippus the student of Iamblichus also gave a concise explanation of Aristotle's book, but he proposed mainly to resolve the problems (aporias) raised by Plotinus, which he put forward in dialogue form. Dexippus, however, added virtually nothing to the considerations of Porphyry and Iamblichus.6

Chapter 2, Movimento, treats Ennead VI.1. 15-22 and VI.3.21-7. This discussion involves Plotinus again in the history of metaphysics, insofar as Aristotle attempts to define movement or change in answer to Eleatic puzzles and in particular to puzzles adumbrated in the third hypothesis of Plato's Parmenides. Aristotle defines movement as incompleteness in energeia, to which Plotinus responds in VI.1.16.5-9 that, on the contrary, movement has already attained its actuality; it is only incomplete with respect to something else, whose existence is consequent upon the movement. Plotinus' strategy against Aristotle involves pointing out logical difficulties in claiming that the energeia of a movement achieves its telos instantaneously, while the movement itself always requires the passage of time (VI.1.16.26-28). In his discussion of movement, Plotinus focuses on the limitations of Aristotle's own exploitation of the causality of his essences. For example in VI.3.23.5-13, Plotinus again denies that motion takes place between the two terminal points delineated by Aristotle, in saying that "walking is not in the feet but an actuality proceeding from a potency to encompass the feet."7Kinesis, as one of Plato's greatest kinds, belongs to the intelligible world, and so movement cannot be the result of the material components that manifest it, i.e., are moved. Instead, Plotinus says that movement is "form awake," stirring to life; in its superior form movement is the potentiality for something to come into being. Generally here Plotinus targets Aristotle as not providing a coherent account of coming into being, just as previously he did not provide a coherent account of being, or substance.

C. returns in chapter three, Analogia, to consider substance again, this time focusing on Plotinus' extension of the concept of genus in 6.1.3 that stems from Aristotle's notion of focal equivocity, to use Owen's term, or quasi-homonymous predications from one, ἀφ'ἕνος. Here he seems to be discussing the P-series with respect to the logic of such a series. Plotinus uses Aristotle's example of the Heraclidae (cf. Metaphysics1058a24): they are homonymously predicated because they all descend from Heracles. Just so, substances are called such because they derive from being in the intelligible sense. Consequently, sensible substances are not actually substances; they have no independent reality. Such a substance is really just a quality.

C. then moves to the later tradition, to Porphyry and Dexippus, and shows how Dexippus tries to recuperate an Aristotelian sense of substance for the Platonist tradition. C. quotes Dexippus' refutation of Plotinus showing that, while Plotinus would have genuine substance stand at the head of a series or taxis, from which the sensible pseudo-substances derive, in fact, Plotinus is simply misreading Aristotle here. Dexippus insists that Aristotle's concern is with the linguistic expressions which are used for substantial predication, and so Plotinus' investigation concerning substances is pointless. C. also gives examples of how Plotinus' own quasi-genus, in which entities are derived from their sources seated in the intelligible world, works in other aspects of his philosophy, as for example in his ethics. (Here he makes use of Linguiti's work on Ennead I.4.8)

C. is concerned to show how Plotinus' initial criticisms of the Aristotelian Categories in fact inaugurated, somewhat paradoxically, the tradition of harmonizing Plato and Aristotle which was the hallmark of later Neoplatonism. Further, he begins to develop a method of reading treatise VI.1 in terms of the broader structure of Plotinus' philosophy, replacing some of the more reactionary readings that see VI.1 as a specious and incoherent attack on Aristotle's work. In pursuing these laudable goals, C. largely succeeds. On the whole, however, I had the feeling that C.'s book, while admirable indeed for its thorough scholarship and careful research into the tradition, tries to accomplish too much. It seems to conclude with a number of results concerning Plotinus' place in the tradition, his methods of dialectic, his use of his own predecessors, that do not, in the end, amount to a real advance in the scholarship. Perhaps this result is reasonable, given that the book represents a revised version of his doctoral thesis. The book makes for difficult reading because the chapters are extremely long (almost one hundred pages in the case of the first chapter) and because it is not clear why C. singles out substance, motion, and analogy as the central locus of Plotinus' attacks. This book is a good overview of work on Plotinus' logic carried out by Lloyd, Strange, and Gerson (as well as fine Italian scholars such as Linguiti, D'ancona Costa, and Parente) but leaves us hankering for more details about the place of Porphyry's work among later Neoplatonists, about the importance of Iamblichus in the transmission of the fragments of Porphyry's lost ad Gedalium, and about Porphyry's understanding of Aristotle's philosophy as a whole.

[[For a response to this review by Riccardo Chiaradonna, please see BMCR 2004.07.02.]]

Notes:

1. Neoplatonist scholars will be aware that Strange had already shown that Plotinus' attacks specifically on the Aristotelian concept of substance deeply informed his student Porphyry's treatment of the work in his On the Categories and Isagogia, as C. readily acknowledges. Cf. Stephen Strange, Plotinus, Porphyry, and the Neoplatonic Interpretation of the Categories, in Aufstieg und Niedergang der Römischen Welt II.36.2, Berlin-New York 1987, pp. 955-74. 2. See Gerson, Plotinus, London: Routledge1994, pp. 79-96, on the structure of Enneads VI.1-3: VI.1 contains Plotinus' anti-Aristotelian and anti-Stoic dialectic; VI.2 develops Plotinus' own theory of categories of the intelligible universe, employing the "greatest genera" of Plato's Sophist, 254D-257A; and VI.3 represents Plotinus' own explication of the structure of sensible substance by means of his own revised categories. 3. Chiaradonna studies the sources of some of Plotinus' arguments against the Aristotelian idea of genus and traces them back to Nicostratus and Lucius. A.C. Lloyd, in his seminal article of 1956, 'Neoplatonic Logic and Aristotelian logic,' Phronesis I pp. 58-72, had of course already shown this continuity. But anyone who has read Lloyd knows that his richly suggestive remarks could at times be compressed, and this is one strain of Lloyd's research that Chiaradonna documents more fully. 4. A. C. Lloyd, The Anatomy of Neoplatonism Oxford: Oxford University Press 1990, pp. 76-79. Steven Strange developed a sophisticated analysis of the functions that such series enjoy within the structure of Plotinus' own metaphysics in his University of Texas dissertation of 1981. 5. For my money this question has already been well addressed in Gerson's Plotinus, pp. 84-93. There is, according to Gerson, a real sense in which Plotinus is right to point out the priority of substance, in Aristotle's own account in Metaphysics Lamba, as pure actuality. 6. Thanks to Michael Chase for pointing out this citation, which exactly captures the point that C. makes with regard to the influence of Plotinus on the tradition. 7. Translation of Michael Wagner in "Plotinus on the nature of physical reality," in Gerson (ed.), The Cambridge Companion to Plotinus, Cambridge: Cambridge University Press 1996, pp. 130-170. In general, it seems to me that in this section of the book C. follows Wagner very closely, and indeed, he himself acknowledges that Wagner's very astute analysis of Plotinus' criticisms of Aristotle's notion of coming to be is central to his own analysis. 8. A. Linguiti, La felicità et il tempo: Plotino, Enneadi, I 4- I 5. Milan: 2000.